I am building a n scale 40x84 layout, and am considering using 1/4 inch ply under 2 inch pink insulation board. Is this doable or a bad idea?
What are you using for the benchwork? 1"x3" benchwork, with cross support, and 2" foam is ample for a layout. Why waste time, money and effort adding an unnecessary layer of 1/4" plywood?
I would put in the 1/4" plywood, especially if you cut into the 2" foam for below track scenery. It will also keep your benchwork frame square.
Working through 2" foam and ply is a real pain. I am in the foam only camp with 2".
Would the 1/4’’ plywood give you something solid to screw mount a switch machine to it?
Although you would need to route out the 2’’ foam so the metal rod of the switch machine will have travel to move the throw bar.
I would be afraid the 1/4" ply would tend to warp the foam unless it was securely attached to the 1x3 underframe.
For the size of your layout, 1/4 inch would be fine. It never hurts to have something solid under the foam to prevent sagging or breakage - like when a visitor presses down on it, etc. (you get the idea).
Just glue a small square of 1/4" ply to the foam under the T/O.
[quote user=“BATMAN”]
Working through 2" foam and ply is a real pain. I am in the foam only camp with 2".
@Batman - My plan is to build similarly to how you do. But - How do you handle the track transitions from roadbed-flat-on-the-foam to the cookie-cutter uphill sections, avoiding vertical kinks? Do you sink the roadbed into the foam for a distance, attaching it through the foam to the wood below, or …? It looks like your risers go through a hole in the foam to reach down to the wood frame, right?
I’m getting past the track planning stage to how am I actually gonna build this - seems like a lot of fundamental architecture decisions to be made.
Thanks for any tips, from others too - Gerhard
Right.
Yes, I just lower the roadbed into the foam to start an incline or to get the track down to the foam for yard situations.
The ply you see in this pic is the only spot that has ply under the foam. It is 1/2" and I put 1-1/2" foam on top of it so it is level with the 2". I did it for structural reasons for the curved end of the benchwork and that is where the TT and RH go.
To lower the cork into the foam I just score it in seconds using a ruler in 1/4" squares which then break off easily. I mark the Exacto knife with a marker to show how deep to cut and then cut down on an angle until I hit the depth as shown on the knife. I put caulk in the trench as it works as a great leveler.
I have built modules with and without the plywood. The span between supports is important. I do have some mechanical under table turnout controls, blue point and bull frog, mounted on a three inch piece of ply, and that assembly mounted to the foam with glue and long screws for a bit of added stabillity. These have never failed and are still reliable after 10 years and moving the modules often. Since I am in Comifornia the 2" stuff is hard to find but I can get 1". So I added some good quality bircth 1/4" ply from Ganahl Lumber and it works great. I can screw things in whereever I want without adding extra supports. Ganahl’s has some great lumber at a higher price point but the stabillity is worth the expense in my opinion.
I hope that helps. There is no best way but rather what you can make work and am happy with.
1x3 open grid spaced 16" on center. Since I like having some space to catch derailments if they occur, I decided to go 48x96, with 3 and 1/2 inch borders as a minimum. That will also give added space for larger radius curves.
I am now thinking foam with cork roadbeds, but will use 1" foam glued on top of a second 1"foam and sandwich the wiring between the two layers, I like the cork because it can be sanded smooth.
I don’t like that idea. You need to keep your wiring accessible. Digging for it while buried in foam is not good or fun.
Drill holes in the 1"x3" cross supports and run the wiring through the holes.
Brent - Thanks for taking the time for such a detailed reply with the photos. It’s always a bit scary the first time you actually do something, no matter how much you’ve read on the 'net! This will definitely improve my confidence, and I’m sure it will help others too.
I also used this method after getting advice from Brent. I also had never attempted something like this. It was easy and worked well.
Hello All,
That’s a really bad idea!
I completely agree.
A primary reason for using foam as a base is the ability to carve or sculpt terrain features into the foam.
I wouldn’t want to breach a feeder wire sandwiched between two pieces of foam for fear of fire.
Think “Call Before You Dig” from prototypical utility companies.
On my 4’x8’ pike I have no underneath access, it sits on the spare bed in the computer/railroad/spare bedroom.
Originally, the base was 1/2-inch Medium Density Fiber Board covered with 1-inch foam.
I used 2-1/2-inch Luan plywood strips; like a facia extending up from the edge of the MDFB, for stiffening.
The MDFB was heavy and prone to sag, even with the stiffening stringers.
To upgrade the base I made an open grid 4’x8’ frame of 1"x4"s with stringers on 32"x24" with 1/4-inch plywood under the 1-inch foam to replace the MDFB.
This is much lighter and stronger with limited under-pike access.
For my wiring, I cut straight “utility trenches” in the foam; 1/2-inch deep and 1/2-inch wide using a 1/2-inch wide wood chisel.
I used 1/2-inch Split Poly Loom; used for automotive wiring harnesses, press fit into the “utility trenches.”
This allowed me to paint, scenic, and ballast over the wiring while still allowing access.
When I needed to make direction changes (junctions) I used a 2-inch hole saw and cut “utility pits” in the foam, by han
thaks for the replies, some foof for thought!
Niiiice! Since this is a small layout, due to space restrictions, I am using manual throws and running three locos, the benchwork is 1x3, 16 inches on center.
Take a look at Batman’s post and picture. I have a 6 ft wide by 24 ft long HO layout built almost exactly the same with 2 inch pink foam base with no problems!
Mine is totally walk around.
The last layout I built was plywood, that required the ply be cut and raised by adding blocks to the stringers, fot elevations. I made the terrain (mountain) with rolled up paper held by masking tape and covered with MW Scenics plaster cloth.
After seeing your benchwork, I am going to go for the 2" foam.
Do you stack the foam for elevations, or use the old rolled paper method?